High scattering smectic liquid crystal material and display device using the same

ABSTRACT

The present invention relates to a high scattering smectic liquid crystal material and display device using the same. In the present invention, a series of smectic A phase liquid crystals having compact arrangement of crystal domains or a series of smectic liquid crystal mixed materials having a degree of order higher than that of the smectic A phase and an optical texture different from that of the smectic A phase are obtained by mixing a smectic liquid crystal with an organic compound having a high optical anisotropy (Δn) or mixing different types of smectic phases. When used in a smectic stable state liquid crystal display pattern, these materials have high scattering properties and can effectively improve the contrast of a smectic liquid crystal display device. The present invention also improves contrast when it used in a reflective smectic liquid crystal display device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a United States National Stage application filedunder 35 U.S.C. §371 of PCT Patent Application Serial No.PCT/CN2011/085036 filed on Dec. 30, 2011 which claims benefit of andpriority to Chinese Patent Application Serial No. 201110451207.7 filedDec. 29, 2011, the disclosures of all of which are hereby incorporatedby reference in their entirety.

TECHNICAL FIELD

The present invention relates to a high scattering smectic liquidcrystal material and displays using the same, which belong to thetechnical field of optical display materials and display devices.

BACKGROUND OF THE INVENTION

The study on using smectic liquid crystal as display material has ahistory of over 30 years. Monitors using the smectic liquid crystals asthe display materials are reflective display devices, which have nopolarizer plate and backlight, compared with common liquid crystaldisplay devices. Such monitors rely mainly on reflection of externallight, resulting in lower contrast and making commercialization moredifficult.

The study on the smectic liquid crystal material is focused onferroelectric liquid crystal and antiferroelectric liquid crystal thatbelong to smectic A phase and smectic C phase. The ferroelectric liquidcrystal and antiferroelectric liquid crystal materials are used insurface stabilized display devices. Since uniform, perfect and regulararrangement is required for both the liquid crystal molecules and theliquid crystal layers in this kind of devices, and the thickness of aliquid crystal cell is required to be 1 to 2 μm, the manufacturingprocess of such devices is very difficult, and large scale productioncannot be achieved, so the ferroelectric liquid crystal devices have notenter a practical commercial application stage.

There are few smectic liquid crystal materials. WO 2010/070606 A1discloses a method for obtaining a wide-temperature range smectic phase.Actual tests show that the contrast of this material is undesirable,making it infeasible to be used in actual display devices.

Therefore, in the field of display application of multi-stable liquidcrystals, there is an urgent need for a high scattering smectic liquidcrystal material that can be used in display devices having an excellentoptical structure, so as to increase the contrast of the smectic crystaldisplay devices and achieve a good display effect.

SUMMARY OF THE INVENTION

The present invention is directed to a series of smectic liquid crystalmixed materials having high scattering, and the smectic liquid crystalmixed materials having high scattering are successfully applied todisplay devices having an excellent optical structure, in combinationwith a drive method suitable for the display material, thereby obtaininga smectic multi-stable liquid crystal display device that is availablefor commercial applications, has a high contrast and a good displayquality, and is energy saving.

In the present invention, a series of smectic A phase liquid crystalshaving compact arrangement of crystal domains or a series of smecticliquid crystal mixed materials having a degree of order higher than thatof the smectic phase A and an optical texture different from that of thesmectic A phase, for example, the smectic B, H and G, are obtained bymixing smectic liquid crystal compounds of different types or mixing asmectic liquid crystal compound with an organic compound having a highoptical anisotropy (Δn). When being applied in a smectic stable stateliquid crystal display mode, this type of materials have a highscattering state, so the contrast of the smectic liquid crystal displaydevices can be effectively improved. When the present invention isapplied to a reflective smectic liquid crystal display device, a smecticdisplay device having a high contrast is obtained.

In the present invention, a mixed liquid crystal having high scatteringis prepared. The high scattering smectic liquid crystal material of thepresent invention is a mixed liquid crystal material, comprising two ormore compound represented by Formula (I).

In Formula (I), R₁ is C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀ alkenyl,C₁-C₂₀ alkenyloxy, silanyl, siloxanyl and halogenated groups thereof;and C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀ alkenyl, C₁-C₂₀ alkenyloxy,silanyl and siloxanyl and isomers thereof with any —CH₂— substitutedwith —O—, —S—, —CF₂—, —CF₂O—, —CO—, —COO—, —O—CO—, —O—COO—, —CF═CF—,—CH═CF—, —CF═CH— or —CH═CH—;

Preferably, R₁ is selected from the group consisting of: C₁-C₁₅ alkyl,C₁-C₁₅ alkoxy, C₁-C₁₅ alkenyl, C₁-C₁₅ alkenyloxy, C₁-C₁₅ silanyl, C₁-C₁₅siloxanyl and halogenated groups thereof; and C₁-C₁₅ alkyl, C₁-C₁₅alkoxy, C₁-C₁₅ alkenyl, C₁-C₁₅ alkenyloxy, C₁-C₁₅ silanyl and C₁-C₁₅siloxanyl and isomers thereof with any —CH₂— substituted with —O— or—S—.

More preferably, R₁ is selected from the group consisting of: C₁-C₁₀alkyl, C₁-C₁₀ alkoxy, C₁-C₁₀ alkenyl, C₁-C₁₀ silanyl, C₁-C₁₀ siloxanyland halogenated groups thereof; and C₁-C₁₀ alkyl, C₁-C₁₀ alkoxy, C₁-C₁₀alkenyl, C₁-C₁₀ silanyl and C₁-C₁₀ siloxanyl and isomers thereof withany —CH₂— substituted with —O—.

R₂ is CN, F, NCS, NCO, CF₃, CHF₂, CH₂F, OCF₃, OCHF₂, OCH₂F, NO₂, Cl,CH═CF₂ and OCH═CF₂; C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀ alkenyl, C₁-C₂₀alkenyloxy, C₁-C₂₀ silanyl and C₁-C₂₀ siloxanyl, and halogenated groupsthereof; and C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀ alkenyl and C₁-C₂₀alkenyloxy and isomers thereof with any —CH₂— substituted with —O—, —S—,—CF₂—, —CF₂O—, —CO—, —COO—, —O—CO—, —O—COO—, —CF═CF—, —CH═CF—, —CF═CH—or —CH═CH—.

Preferably, R₂ is selected from the group consisting of: CN, F, NCS,CF₃, CHF₂, CH₂F, OCF₃, OCHF₂, OCH₂F, and Cl; C₁-C₁₅ alkyl, C₁-C₁₅alkoxy, C₁-C₁₅ alkenyl, C₁-C₁₅ alkenyloxy, C₁-C₁₅ silanyl, C₁-C₁₅siloxanyl and halogenated groups thereof; and C₁-C₁₅ alkyl, C₁-C₁₅alkoxy, C₁-C₁₅ alkenyl and C₁-C₁₅ alkenyloxy and isomers thereof withany —CH₂— substituted with —O— or —S—.

More preferably, R₂ is CN, F, NCS, CF₃ or OCF₃.

A, B, C and D each has a rigid ring structure and each independentlycomprises:

or cycloalkenyl; wherein the hydrogen atoms X₁ to X₁₄ on the ringstructures are either unsubstituted or indendently substituted with CN,F, CF₃, CHF₂, CH₂F, OCF₃, OCHF₂, OCH₂F, NO₂, Cl, alkyl or alkoxy.

Preferably, A, B, C and D are independently selected from the groupconsisting of:

More preferably, A, B, C and D are independently selected from the groupconsisting of:

Z₁ to Z₃ are independently: a single bond (that is, two rigid moietiesare directly connected), C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀ alkenyl,C₁-C₂₀ alkenyloxy, C₁-C₂₀ silanyl and C₁-C₂₀ siloxanyl; and C₁-C₂₀alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀ alkenyl, C₁-C₂₀ alkenyloxy, C₁-C₂₀ silanyland C₁-C₂₀ siloxanyl and isomers thereof with any —CH₂— substituted with—O—, —S—, —CO—, —COO—, —O—CO—, —O—COO—, —CF═CF—, —CHF—, —CF₂—, —CF₂O—,—CH₂O—, —OCH₂—, —CH═CH—, —CH═N—, —C≡C—, —CH═N—N═CH—, —CH═CF—, —CF═CH—,—CH₂CF₂—, —CF₂CH₂— or

Preferably, Z₁ to Z₃ are independently selected from the groupconsisting of: a single bond, —C₂H₄—, —CH═CH—, —C≡C—, —CF₂O—, —CH₂O—,—COO— and —CH═N—N═CH—.

More preferably, Z₁ to Z₃ are independently selected from the groupconsisting of: a single bond, —C₂H₄—, —CH═CH—, —C≡C—, —CF₂O—, —CH₂O— and—COO—.

X₁ to X₁₄ are independently selected from the group consisting of: H,CN, NCS, F, Cl, CF₃, CHF₂, CH₂F, OCF₃, OCHF₂, OCH₂F, NO₂, alkyl andalkoxy.

Preferably, X₁ to X₁₄ are independently selected from the groupconsisting of: H, CN, NCS, F, C₁ and CF₃.

More preferably, X₁ to X₁₄ are independently selected from the groupconsisting of: H, CN, F and Cl.

M1, M2, M3 and M4 are independently 0, 1 or 2, and M1+M2+M3+M4≧2.Preferably, M1, M2, M3 and M4 are independently 0 or 1, andM1+M2+M3+M4≧2.

When being used as a display material, any compound alone cannot satisfyall requirements, so a variety of compounds having excellentphotoelectric properties are selected and mixed at a certain ratio toform a mixed liquid crystal for the purpose of satisfying variousperformance requirements. Similarly, in order to further improve thedegree of scattering of the smectic liquid crystal material on a basisof ensuring the other excellent properties, selection of the compoundsand the formulation ratio thereof need to be optimized. Therefore, inthe present invention, mixing of different compounds is studied and ahigh scattering mixed smectic liquid crystal material that can improvethe contrast is provided.

In the present invention, a mixed liquid crystal having high scatteringis prepared. In addition to two or more organic compound represented byFormula (I), the high scattering smectic liquid crystal material of thepresent invention may further comprise one or more ionic compoundrepresented by Formula (II).R₃—X⁺Y⁻  Formula (II)

In Formula (II), R₃ is: C₀-C₂₀ alkyl, C₀-C₂₀ alkoxy, C₀-C₂₀ alkenyl andC₀-C₂₀ alkenyloxy, and halogenated groups thereof; ferrocenylmethyl andphenyl; and C₀-C₂₀ alkyl, C₀-C₂₀ alkoxy, C₀-C₂₀ alkenyl, C₀-C₂₀alkenyloxy and isomers thereof with any —CH₂— substituted with —O—, —S—,—CF₂—, —CF₂O—, —CO—, —COO—, —O—CO—, —O—COO—, —CF═CF—, —CH═CF—, —CF═CH—,—CH═CH—,

or phenyl.

Preferably, R₃ is selected from the group consisting of: C₀-C₁₆ alkyl,C₀-C₁₆ alkoxy, C₀-C₁₆ alkenyl, C₀-C₁₆ alkenyloxy, ferrocenylmethyl andphenyl; and C₀-C₁₆ alkyl, C₀-C₁₆ alkoxy, C₀-C₁₆ alkenyl and C₀-C₁₆alkenyloxy and isomer thereof with any —CH₂— substituted with —O—, —S—,

and phenyl.

More preferably, R₃ is selected from the group consisting of: C₀-C₁₆alkyl, phenyl; and C₀-C₁₆ alkyl and isomers thereof with any —CH₂—substituted with

and phenyl.

X⁺ is a cation selected from the group consisting of: Na⁺, K⁺, N⁺,[(R₄)₃]N⁺, [(R₄)₃]P⁺,

wherein R₄ is C₁-C₃₀ alkyl, C₁-C₃₀ alkoxy, C₁-C₃₀ alkenyl, C₁-C₃₀alkenyloxy or halogenated groups thereof, or phenyl, and R₅ is C₁-C₃₀alkyl, C₁-C₃₀ alkoxy, C₁-C₃₀ alkenyl, C₁-C₃₀ alkenyloxy, or halogenatedgroups thereof, or phenyl.

Preferably, X+ is a cation selected from the group consisting of: Na+,K+, N+, [(R4)3]N+, [(R4)3]P+,

wherein R4 is C1-C20 alkyl, C1-C20 alkoxy, C1-C20 alkenyl, C1-C20alkenyloxy, or halogenated groups thereof, or phenyl; and R5 is C1-C20alkyl, C1-C20 alkoxy, C1-C20 alkenyl, C1-C20 alkenyloxy, or halogenatedgroups thereof, and phenyl.

More preferably, X+ is a cation selected from the group consisting of:Na+, K+, N+, [(R4)3]N+, [(R4)3]P+,

wherein R4 is C1-C16 alkyl or phenyl; and R5 is C1-C16 alkyl or phenyl.

Y⁻ is an anion selected from the group consisting of: F⁻, Cl⁻, Br⁻, I⁻,(PF₆)⁻, (Ph₄B)⁻, SO₄ ⁻, ClO₄ ⁻ and

Preferably, Y⁻ is an anion selected from the group consisting of: F⁻,Cl⁻, Br⁻, (PF₆)⁻, (Ph₄B)⁻, SO₄ ⁻, ClO₄ ⁻; and

More preferably, Y⁻ is an anion selected from the group consisting of:F⁻, Cl⁻, Br⁻, (PF₆)⁻, (Ph₄B)⁻, SO₄ ⁻ and ClO₄ ⁻.

Most preferably, the ionic compound represented by Formula (II) has astructure represented by Formula (VII),

wherein R is selected from the group consisting of: C₀-C₁₆ alkyl andC₀-C₁₆ terminal alkenyl; and

X⁻ is an anion selected from the group consisting of: F⁻, Cl⁻, Br⁻,(PF₆)⁻, (Ph₄B)⁻, SO₄ ⁻ and ClO₄ ⁻.

In the present invention, a series of mixed liquid crystals havingcompact arrangement of crystal domains are obtained with the novel highscattering smectic liquid crystal material through mixing, so that thelight entering the mixed liquid crystals exhibit a higher scatteringstate. The high scattering smectic liquid crystal material of thepresent invention may be a smectic A phase or a non-smectic A phaseliquid crystal material, where the non-smectic A phase liquid crystalmaterial may be a smectic B, C, D, E, F, G, H, or I phase material, or aundefined smectic X phase materials having a degree of order higher thanthat of the smectic A phase. The mixed material may be used in existingsmectic liquid crystal display devices, and the contrast of the existingdisplay devices can be effectively improved.

The high scattering smectic liquid crystal material of the presentinvention preferably contains a smectic liquid crystal compound and atleast one of a compound A, a compound B and a compound C.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the drive display principle of a smecticliquid crystal.

FIG. 2A shows the texture of a common smectic A phase mischcrystal, andFIG. 2B shows the texture of a smectic A phase mischcrystal having largecrystal domains obtained by mixing according to the present invention(shot by using a 10× objective lens).

FIG. 3A and FIG. 3B are views of the textures of a non-smectic A phasemischcrystal obtained by mixing according to the present invention (shotby using a 10× objective lens).

FIG. 4 is a schematic view of an instrument for testing the contrast bya microscopy method.

FIG. 5 is a view of the texture of a smectic A phase mischcrystalaccording to Embodiment 1 (shot by using a 10× objective lens).

FIG. 6 is a view of the texture of a non-smectic A phase mischcrystalaccording to Embodiment 2 (shot by using a 10× objective lens).

FIG. 7 is a view of the texture of a mischcrystal according toEmbodiment 11 (shot by using a 10× objective lens).

FIG. 8 is a schematic view of a display layer of a smectic liquidcrystal display module.

FIG. 9 is a schematic view of a light-enhancing layer of a smecticliquid crystal display module.

DETAILED DESCRIPTION OF THE INVENTION

In the present invention, the following aspects are studied.

1) Long-Carbon Chain Smectic Materials

50 wt % cyanobiphenyl compounds having different carbon chain lengthsare mixed with 50 wt % I102 and 10OCB, where I102:10OCB=4:1 (weightratio). After mixing, 4 wt ‰ cetyltrimethyl ammonium perchlorate isadded, to prepare a liquid crystal mixed layer; and then, thetransmittance at clearing state, the transmittance at frosting state andthe contrast are tested, with the results shown in Table 1.

Linear cyanobiphenyl compounds are a very important class of compounds,and are the smectic A phase materials when the number of carbon in thechain section is higher than 8. It can be seen that, long carbon chainis favorable for the formation of the smectic phase, so it is supposedthat the contrast may be improved by extending the carbon chain.Therefore, the linear cyanobiphenyl compounds having different carbonchain lengths are compared (data is shown in Table 1); however, it isfound that 8CB with the shortest chain has the best effect.

TABLE 1 Influence of cyanobiphenyl compounds having different carbonchain lengths on the contrast Content in formulation (wt %)Cyanobiphenyl Trans- having different mittance carbon chains at clearingTransmittance (50 wt %) (50 wt %) state at frosting state ContrastI102:10OCB =  8CB 90% 22% 4.09:1 4:1  9CB 90% 23% 3.91:1 10CB 90% 23%3.91:1 11CB 90% 24% 3.75:1 12CB 90% 24% 3.75:1 13CB 90% 25%  3.6:1 14CB90% 26% 3.46:1 15CB 90% 30% 3.00:1 16CB 90% 30% 3.00:1 Note The aboveformulations contain 4 wt % cetyltrimethyl ammonium perchlorate;

the figure before CB represents the number of carbon atoms in the carbonchain

2) Reduction of Amount of Siloxane Liquid Crystals

Different amounts of I102 are mixed with 10OCB, 8CB and B1, where10OCB:8CB:B1=1:2:1 (weight ratio). After mixing, 4 wt ‰ cetyltrimethylammonium perchlorate is added, to prepare a liquid crystal mixed layer;and then, the transmittance at clearing state, the transmittance atfrosting state and the contrast are tested, with the results shown inTable 2.

The structure of the siloxane liquid crystal molecule contains aflexible and large siloxanyl group, the flexible long chain section ofthe siloxane liquid crystal molecule is long, the ratio of the volume ofthe flexible moiety in the whole molecular size is large, and generally,the interstice caused by arrangement of the flexible moiety in thesmectic layer is higher than that caused by the rigid moiety, so the“interstices” in the smectic layer formed in siloxane liquid crystal aremore, and the probability of the light passing through these“interstices” is large at frosting state. Therefore, the transmittanceat frosting state is large, and the contrast is low. In theory, thecontrast may be improved by reducing the content of the siloxane liquidcrystal in the formulation. A series of experiments show that when theamount of siloxane liquid crystals is lower than 10%, the contrast canbe up to 5:1.

TABLE 2 Data of influence of the content of siloxane liquid crystals onthe contrast Content in formulation (wt %) Transmittance Transmittance10OCB:8CB = 1:2 I102 at clearing state at frosting state Contrast 50 5090% 30% 3.00:1 55 45 90% 30% 3.00:1 60 40 90% 25% 3.60:1 65 35 90% 22%4.09:1 70 30 90% 22% 4.09:1 75 25 90% 21% 4.28:1 80 20 90% 20% 4.50:1 8515 90% 19% 4.73:1 90 10 90% 18% 5.00:1 95 5 90% 18% 5.00:1 Note Theabove formulations contain 4 wt ‰ cetyltrimethyl ammonium perchlorate.

3) Addition of Compounds Having a Large Optical Anisotropy (Δn) forMixing

the contrast of the liquid crystal material is significantly correlatedwith the optical anisotropy (Δn) of the liquid crystal material, and ingeneral, the liquid crystal material having a high optical anisotropy(Δn) has a high contrast, so it is tried to adding a liquid crystalmaterial having a high optical anisotropy (Δn) for mixing.

A) Addition of Alkyne Liquid Crystals

In the nematic phase formulation, in order to improve the contrast ofthe liquid crystal, an alkyne liquid crystal material having a highoptical anisotropy (Δn) is often added. It is found that addition of thealkyne liquid crystal can improve the contrast of the smectic liquidcrystal formulation; however, it is found through repeated experimentsthat the change of the contrast of the smectic phase formulation varieswith the amount of the alkyne liquid crystal material, that is, at thebeginning, the contrast of the smectic phase formulations graduallyincreases with the increase of the amount of the alkyne liquid crystalmaterial, and after the contrast reaches 7.5:1, the contrast maintainsconstant and then gradually drops with the increase of the amount of thealkyne liquid crystal material, with the specific date shown in Table 3.

TABLE 3 Experimental data of addition of alkyne liquid crystal toimprove the contrast Trans- Content in formulation (wt %) mittanceI102:8CB = Alkyne liquid at clearing Transmittance 1:4 crystal state atfrosting state Contrast 100  0 90% 30% 3.00:1 95 5 90% 22% 4.09:1 90 1090% 15% 6.00:1 85 15 90% 12% 7.50:1 80 20 90% 12% 7.50:1 75 25 90% 15%6.00:1 70 30 90% 15% 6.00:1 65 35 90% 22% 4.09:1 60 40 90% 30% 3.00:1Note The above formulations contain 4 wt % cetyltrimethyl ammoniumperchlorate; and the alkyne liquid crystal has a structure below:

The method for improving the contrast by adding an alkyne liquid crystalis not limited to the materials having the structures above, andaddition of the alkyne liquid crystal materials having a structure otherthan the structures of Formulas above can also improve the contrast.

B) Addition of Cyanoterphenyl Liquid Crystals

5CT (n-pentyl cyanoterphenyl) materials are a type of materials that arecommercially available and have a high optical anisotropy (Δn), and areused in some experiments. It is found that when the content of 5CT ishigher than 20 wt %, it is difficult to dissolve, and when the contentis increased to 10%, the limit of the contrast is reached, and furtheraddition had no contribution to the contrast, with the data shown inTable 4.

TABLE 4 Influence of the content of 5CT on the contrast Content informulation (wt %) Transmittance Transmittance I102:8CB = 1:4 5CT atclearing state at frosting state Contrast 70 30 — — — 75 25 — — — 80 2090% 15% 6:1 85 15 90% 15% 6:1 90 10 90% 15% 6:1 95 5 90% 18% 5:1 100 090% 30% 3:1 Note The above formulations contain 4 wt ‰ cetyltrimethylammonium perchlorate; and — represents cannot be dissolved.

C) Addition of Polycyclic Materials

In general, the larger the conjugated moiety in the liquid crystalmaterial, the higher the optical anisotropy (Δn), where the conjugatedmoiety in the material generally depends on the rigid moiety, and therigid moiety generally formed by multiple rigid rings throughconnection. By comparison of multiple polycyclic materials, a polyphenylmaterial having an excellent performance is found, which has a contrastof up to 8:1, with data shown in table 5.

TABLE 5 Influence of polycyclic materials on the contrast Content informulation (wt %) 80% 20% Contrast I102:8CB = 1:4

6:1

5:1

5:1

8:1

6.5:1   Note The above formulations contain 4 wt % cetyltrimethylammonium perchlorate.

D) Addition of Heterocyclic Liquid Crystals for Mixing

A heterocyclic liquid crystal generally has an optical anisotropy (Δn)higher than that of a liquid crystal having a similar structure. In theexperiments of mixing smectic liquid crystals, it is found that when theliquid crystal monomer in the formulation is replaced by a heterocyclicliquid crystal having a similar structure, the contrast is significantlyimproved, with the specific experimental data shown in Table 6. It isfound by analyses that, due to addition of some heterocyclic liquidcrystals, small crystal domains in the focal conic texture of thesmectic A phase become much larger, and it is found that the size of thecrystal domains is 5 to 10 times larger than the size of the crystaldomains of the common smectic A phase formulations through observationwith a polarizing microscope. FIG. 2A shows the texture of the commonsmectic A phase mischcrystal. FIG. 2B shows the texture of the smectic Aphase mischcrystal having compact arrangement of crystal domainsobtained by mixing according to the present invention (shot by using a10× objective lens). The contrast of the material according to thepresent invention is 9:1; and in some cases, even a contrast of 12:1 ofother material having non-smectic A phases can be obtained, with thetexture shown in FIG. 3A and FIG. 3B. Therefore, in order tosignificantly improve the contrast of the smectic liquid crystalformulations, the degree of order of molecular arrangement of thesmectic liquid crystal needs to be improved, and the apparent appearanceis that the optical texture of the smectic phase is more compact and thecrystal domains are larger.

TABLE 6 Data of improvement of the contrast by heterocyclic liquidcrystals Content in formulation (wt %) 70% 30% Contrast I102:8CB = 1:4

3:1

9:1

10:1 

4:1

10:1  Note The above formulations contain 4 wt % cetyltrimethyl ammoniumperchlorate.

The methods for expanding the smectic A phase crystal domains orobtaining the non-smectic A phase textures by adding heterocyclic liquidcrystals are not limited to addition of the materials having the abovestructures, and addition of heterocyclic liquid crystal materials havinga structure other than the structures represented by the structuralformulas above can also improve the contrast.

It is found through the tests above, the contrast can be improved byadding one or more of four materials below to the common smectic A, B,C, D, E, F, G, H or I phase liquid crystal materials, such as thesmectic A phase materials (I102, 8CB).

a. Alkyne Liquid Crystals

where R₆ is C₁-C₁₀ alkyl or C₁-C₁₀ alkoxy;

R₇ is CN, NCS or F.

E and F are independently selected from the group consisting of:

X₁₅ to X₂₀ are independently selected from the group consisting of: Hand F.

M₅ and M₆ may independently be 0 or 1.

b. Heterocyclic Rings

where R₈ is C₁-C₁₀ alkyl or C₁-C₁₀ alkoxy;

R₉ is CN, NCS or F.

G and H are independently selected from the group consisting of:

X₂₁ to X₂₂ are independently selected from the group consisting of: Hand F.

M₇ and M₈ may independently be 0 or 1, and M₇+M₈≧1.

c. Difluoro Ethers

where R₁₀ is C₁-C₁₀ alkyl or C₁-C₁₀ alkoxy;

R₁₁ is CN, NCS or F.

The ring structure I is selected from the group consisting of:

X₂₃ to X₂₈ are independently selected from the group consisting of: Hand F.

M₉ may independently be 0 or 1.

d. Polycyclic Biphenyls

where R₁₂ is C₁-C₁₀ alkyl or C₁-C₁₀ alkoxy;

R₁₃ is CN, NCS or F.

The ring structure J and K are selected from the group consisting of:

Z₄ is selected from the group consisting of: a single bond, —COO—,—C₂H₄— and

X₂₉ to X₃₂ are independently selected from the group consisting of: Hand F.

M₁₀ and M₁₁ may independently be 0 or 1.

4) Addition of Other Smectic Phases for Mixing

According to the molecular arrangement and texture, the smectic liquidcrystals are classified into different phases, namely, the smectic A, B,C, D, E, F, G, H and I, where the smectic A phase has the lowest degreeof order. It is found through a large number of experiments that whenbeing mixed with the other smectic liquid crystals, the crystal domainsof the smectic A phase are significantly expanded, and the contrast isimproved; and in some cases, a smectic phase having a optical textureother than the smectic A phase may be obtained, and once themischcrystal is changed into a non-smectic A phase, the contrast issignificantly improved. The reason is that the liquid crystals with theother smectic phases have a relatively high degree of order, and thedegree of order of the mischcrystal is increased by mixing with othermaterials. The basic method includes mixing the compounds of Formula (I)with the smectic B, C, D, E, F, G, H or I phase liquid crystal materialsindependently, and the smectic A, B, C, D, E, F, G, H and I phasemischcrystal materials, even some undefined new mischcrystal materialscan be obtained by adjusting the ratio.

In addition, a mixture having a degree of order higher than that of thesmectic A phase can be obtained by mixing the non-smectic A phasesmectic liquid crystal material with some compounds having alength-diameter ratio, thereby achieving the purpose of improving thecontrast.

In the present invention, the contrast of the smectic display devices isimproved by modifying the optical texture of the common smectic A phase.The specific technical means include, but not limited to, mixing withthe heterocyclic liquid crystals, and mixing with different smecticmaterials. The high scattering smectic liquid crystal material obtainedin the present invention is a smectic A phase material or a mischcrystalmaterial of the smectic B, C, D, E, F, G, H or I phase having a degreeof order higher than that of the smectic A phase.

In the smectic liquid crystal display device, the high scatteringsmectic liquid crystal material of the present invention may be combinedwith a spacer, in some cases also with a polymer, to form a mixed liquidcrystal layer of a smectic liquid crystal display. In the mixed liquidcrystal layer formed by the high scattering smectic liquid crystalmaterial of the present invention, the content of compound representedby Formula (I) is 1 wt % to 100 wt %, preferably 10 wt % to 100 wt %,based on the total weight of the mixed liquid crystal layer; the contentof the ionic compounds, preferably such as cetyltrimethyl ammoniumperchlorate, is 0.0001 wt % to 10 wt %, preferably 0.0001 wt % to 1 wt%, based on the total weight of the mixed liquid crystal layer.

The drive display principle of the smectic phase liquid crystal appliedto display is shown in FIG. 1. The smectic liquid crystal display screengenerally includes an upper base plate and a lower base plate coatedwith an electrode layered structure and a mixed smectic liquid crystalsandwiched between the upper base plate and the lower base plate, andthe mixed liquid crystal layer is generally formed by mixing a smecticliquid crystal, a conductive material, a spacer and sometimes a polymer.A capacitor structure formed by crossed electrodes from the upper andlower base plates is connected to an external drive circuit so thecapacitor can apply electric energy to the mixed liquid crystal layerbetween the base plates, wherein the applied waveform may behigh-frequency drive pulse for clearing operation and low-frequencydrive pulse for frosting operation.

In a low frequency electric field (≦100 Hz), long-chain conductive ions(the conductive material, such as added organic conductive ions, such astetrabutylammonium bromide, sodium laurylsulfate, cetyltrimethylammonium perchlorate, and tetraphenylphosphonium iodide) begin to moveback and forth under the electric field force, thereby agitating anddisturbing the smectic layer in ordered arrangement. This behavior issimilar to the dynamic scattering effect of the nematic liquid crystal,and difference lies in that, the vortex plane formed during the smecticdynamic scattering is perpendicular to the direction of the appliedelectric field, while the vortex plane formed during the dynamicscattering of the nematic liquid crystals is parallel to the directionof the applied electric field. The molecular arrangement of the smecticliquid crystal is kept in a disordered state as shown in the lower leftpanel of FIG. 1 due to the high viscosity of the smectic liquid crystal.At this time, when observing the liquid crystal cell by using thetransmittance light from a microscope, it can be viewed that theelectrode region is in a back state that shads light, resulting in afrosting state.

In high-frequency electric field (≧1000 Hz), the organic conductive ionsmove back and forth slightly, and the agitation effect on the liquidcrystal is negligible. Herein, under the electric field force, the majoraxis of the liquid crystal molecules are oriented in parallel to thedirection of the electric field; when the electric signal is stopped,this regular arrangement is maintained, as shown in the right side inthe figure below. At this time, when observing the liquid crystal cellby using the transmittance light from a microscope, it can be viewedthat the electrode region is in a bright state that light can transmit,resulting in a clearing state.

The molecular arrangement of the smectic liquid crystal can also remainin various states where the light transmittance is different, so as toachieve display at different grey levels. Therefore, the smectic liquidcrystal may have the feature of multi-stable states.

The high scattering smectic material of the present invention can alsobe filled between two plastic films or two pieces of glass with aconductive layer and serving as a dimming medium, and can also be filledin vacuum into a lattice screen to serve as a display device.

In order to control the thickness of the liquid crystal cell, in thehigh scattering smectic material of the present invention, a spacerball, a spacer rod made of polyester or polystyrene, or a glass materialmay be added; in order to reduce the working viscosity and improve thebonding firmness of the liquid crystal cell, a prepolymer may be addedin the high scattering smectic material; and in order to achieve theeffect of color display, a dichroic dye may be added in the highscattering smectic material.

The high scattering smectic material of the present invention is notlimited to be used as a material in the dimming medium or a displaydevice, and can be used in all the devices with a dual-frequency drivemode of low-frequency frosting and high-frequency clearing.

Advantages of the Present Invention

1. In the present invention, a new method for mixing the smectic liquidcrystal material is used to obtain a series of smectic A phase liquidcrystals having compact arrangement of crystal domains or a series ofsmectic liquid crystal mixed materials having a degree of order higherthan that of the smectic A phase and an optical texture different fromthat of the smectic A phase, for example, the smectic B, H and G, andwhen being applied in a multi-stable smectic liquid crystal displaypattern, this type of materials have a high scattering state.

2. When being applied to an existing smectic liquid crystal display, themixed material of the present invention can effectively improve thecontrast of the existing display. The contrast acceptable for human eyesis generally 5:1, and the high scattering smectic material provided bythe present invention have a contrast of 6:1 to 12:1 without any opticalprocessing aids, thereby providing good visual effects.

The present invention is further described below with reference to theaccompanying drawings and specific embodiment, which are not intended tolimit the scope of the present invention.

In the present invention, mixing and tests are performed following thefollowing liquid crystal mixing experimental procedure:

1. selected materials are weighed at a specified ratio, and are addedone by one into a glass vial;

2. the vial containing the materials is placed in an oven and heateduntil the liquid crystal is completely clear;

3. the liquid crystal is fully and uniformly mixed through ultrasonicshock or magnetic stirring;

4. the mixed liquid crystal is heated and filled into a liquid crystalcell having a thickness of 12 micrometers;

5. at a voltage of ±40 V, frosting is performed on the liquid crystalcell at a frequency of 30 Hz and clearing is performed at a frequency of2 KHz, with all waves in the form of square waves; and

6. the liquid crystal cell was tested for the contrast.

The contrast of the smectic liquid crystal display is a ratio of thelight transmittance at the clearing state to the light transmittance atthe frosting state for the device, and in general, all materials havesubstantially the same light transmittance at the clearing state;therefore, the contrast mainly depends on the light transmittance of thematerial at the frosting state, that is, the scattering state of thesmectic liquid crystal material.

Since no standard method for testing the contrast of the reflectivesmectic liquid crystal display device is available in the industry,multiple universal and simple methods are used to test the contrast, andfinally, a test method having a visual effect closer to that of humaneye is selected and used as the standard of verification and comparison.

Contrast Test Method: Microscopy Method

This test method is a simple method that is often used for testing andhas measurement results close to human eyes, and the apparatus used bythe method is shown in FIG. 4. In the microscopy method, a lighttransmittance measurement system HL-TT-MS is used as the contrast testapparatus, a DM_(—)2500M metalloscope from Leica Corp. is used as theimaging device, an MV-VD120SC industrial CCD camera from MicrovisionInc. is used as the optical signal collector, and HL-CR-11A softwarefrom Halation Photonics Co., Ltd. is used as the numerical calculationsoftware.

Test Procedure:

1. A sample is placed on an objective table, and the focal length of themicroscope is adjusted, so that the sample can be imaged clearly.

2. The sample was removed, and the HL-CR-11A software was used tocompute with the numerical values at each points collected by CCD asfollows:Yi=0.299*R+0.587*G+0.114*B.

3. The Yi values at each points are summed to give a normalized factorY0=ΣYi.

4. The sample is placed onto the objective table, and the HL-CR-11Asoftware is used to compute the Y value at this point Y=ΣYi.

5. The transmittance of the sample is defined as T=(Y/Y0)*100%.

6. For the smectic liquid crystal sample, the transmittance at clearingstate Tc=(Yc/Y0)*100%, the transmittance at frosting stateTs=(Ys/Y0)*100%, and the contrast Cr═Tc/Ts.

In brief, first, in the situation that no liquid crystal cell is placedon the objective table and a light source (light ray emitted from ahalide lamp equipped on the microscope) directly enter the objectivelens, the light rays are collected by a receiver, the receiver convertsthe collected light rays into corresponding electric signals and sendthe electric signals to software of a computer, and the software recordsan electric signal B at this point as a basic reference value. Next, theluminance L of the light source at this point is fixed, the liquidcrystal cell is placed on an objective table and the height of theobjective table is adjusted, so that the liquid crystal cell can beclearly observed from an ocular lens; the receiver converts the lightray energy collected from the liquid crystal cells at the clearing stateand the frosting state into an electric signal and sent the electricalsignal to the computer. The computer software compares the light rayenergy received at the clearing state and the frosting state with thebasic reference. That is, the electric signal Q of the light ray energyreceived at the clearing state is divided by the basic reference value Bto obtain a transmittance value QL at the clearing state, the electricsignal M of the light ray energy received at the frosting state isdivided by the basic reference value B to obtain a transmittance valueML at the frosting state, and the transmittance at the clearing state isdivided by the transmittance at the frosting state to obtain a contrastvalue QL/ML*100%.

Embodiment 1 High Scattering Smectic A Phase Mischcrystal Having LargeCrystal Domains Obtained by Using Heterocyclic Liquid Crystals

TABLE 7 Composition the mischcrystal of Embodiment 1 Materials Content,wt %

40

15

5

10

5

20

4

1

The view of the texture of the mischcrystal in this embodiment is shownin FIG. 5 (shot by using a 10× objective lens). It is observed by usinga microscope that, the texture is the smectic A phase, but hasrelatively large crystal domains that are arranged compactly, and has agood shading effect at the frosting state. The transmittance is testedas 90% at the clearing state and is merely 10% at the frosting state, sothe contrast is 9:1.

Embodiment 2 High Scattering Non-Smectic A Phase Mischcrystal Obtainedby Using Heterocyclic Liquid Crystals

TABLE 8 Composition of the mischcrystal of Embodiment 2 MaterialsContent, wt %

15

25

5

9.9

5

15

20

5 Tetrabutylammonium bromide 0.1

According to the mixing method and the contrast test method inEmbodiment 1, experiments are performed on the formulation in Table 8,and the following embodiment are the same.

As shown in FIG. 6, FIG. 6 is a view of the texture of the mischcrystalof this embodiment (shot by using a 10× objective lens). The texture isobserved by using a microscope, definitely, the liquid crystal is notthe smectic A phase liquid crystal, and it is judged that themischcrystal is similar to that of the smectic B or H phase according tothe texture. The crystal domains are changed from the smectic A needleshape to the irregular blocks shape and have a compact arrangementwithout any interstice therebetween, and a good shading effect isachieved at the frosting state. The transmittance is tested as 84% atthe clearing state and is merely 7% at the frosting state, and thecontrast is 12:1.

Embodiment 3 High Scattering Smectic B Phase Mischcrystal Obtained byUsing the Smectic B Phase for Mixing

TABLE 9 Composition of the mischcrystal of Embodiment 3 MaterialsContent, wt %

20

5

5

5

10

10

19.9

25 Phenyltriethylammonium iodide 0.1

The texture is observed by using a microscope, and the liquid crystal isthe smectic B liquid crystal, has compact arrangement of crystaldomains, and has a good shading effect at the frosting state. Thetransmittance is tested as 90% at clearing state and is merely 9% at thefrosting state, and the contrast is 10:1.

Embodiment 4 High Scattering Smectic C Phase Mischcrystal Obtained byUsing the Smectic C Phase for Mixing

TABLE 10 Composition of the mischcrystal of Embodiment 4 MaterialsContent, wt %

20

10

5

5

10

5

19.9

25 Tetraethylamine p-toluenesulfonate 0.1

The texture is observed by using a microscope, and the liquid crystal isthe smectic C liquid crystal, has compact arrangement of crystaldomains, and has a good shading effect at the frosting state. Thetransmittance is tested as 90% at the clearing state and is merely 10%at the frosting state, and the contrast is 9:1.

Embodiment 5 High Scattering Smectic D Phase Mischcrystal Obtained byUsing the Smectic D Phase for Mixing

TABLE 11 Composition of the mischcrystal of Embodiment 5 MaterialsContent, wt %

20

5

10

5

5

10

5

14.9

25 Bis(tetra-n-butyl- 0.1amine)bis(1,3-dithiole-2-thione-4,5-dithiolato)palladium(II)

The texture is observed by using a microscope, and the liquid crystal isthe smectic D liquid crystal, has compact arrangement of crystaldomains, and has a good shading effect at frosting state. Thetransmittance is tested as 90% at the clearing state and is merely 9% atthe frosting state, and the contrast is 10:1.

Embodiment 6 High Scattering Smectic E Phase Mischcrystal Obtained byUsing the Smectic E Phase for Mixing

TABLE 12 Composition of the mischcrystal of Embodiment 6 MaterialsContent, wt %

20

5

10

5

10

5

19.9

25 Bis(tetra-n-butylammonium)tetracyanodiphenoquinodimethane 0.1

The texture is observed by using a microscope, and the liquid crystal isthe smectic E liquid crystal, has compact arrangement of crystaldomains, and has a good shading effect at the frosting state. Thetransmittance is tested as 90% at the clearing state and is merely 9% atthe frosting state, and the contrast is 10:1.

Embodiment 7 High Scattering Smectic F Phase Mischcrystal Obtained byUsing the Smectic F Phase for Mixing

TABLE 13 Composition of the mischcrystal of Embodiment 7 MaterialsContent, wt %

20

15

10

5

5

10

9.9

25 Cetylammonium perchlorate 0.1

The texture is observed by using a microscope, and the liquid crystal isthe smectic F liquid crystal, has compact arrangement of crystaldomains, and has a good shading effect at the frosting state. Thetransmittance is tested as 90% at the clearing state and is merely 9% atthe frosting state, and the contrast is 10:1.

Embodiment 8 High Scattering Smectic G Phase Mischcrystal Obtained byUsing the Smectic G Phase for Mixing

TABLE 14 Composition of the mischcrystal of Embodiment 8 MaterialsContent, wt %

20

15

10

5

5

5

5

9.9

25 Cetyl tetraammonium bromide 0.1

The texture is observed by using a microscope, and the liquid crystal isthe smectic G liquid crystal, has compact arrangement of crystaldomains, and has a good shading effect at the frosting state. Thetransmittance is tested as 90% at the clearing state and is merely 9% atthe frosting state, and the contrast is 10:1.

Embodiment 9 High Scattering Smectic H Phase Mischcrystal Obtained byUsing the Smectic H Phase for Mixing

TABLE 15 Composition of the mischcrystal of Embodiment 9 MaterialsContent, wt %

20

15

5

5

5

5

19.9

25 1-octyl-3-methylimidazole hexafluorophosphate 0.1

The texture is observed by using a microscope, and the liquid crystal isthe smectic H liquid crystal, has compact arrangement of crystaldomains, and has a good shading effect at the frosting state. Thetransmittance is tested as 90% at the clearing state and is merely 9% atthe frosting state, and the contrast is 10:1.

Embodiment 10 High Scattering Smectic I Phase Mischcrystal Obtained byUsing the Smectic I Phase for Mixing

TABLE 16 Composition of the mischcrystal of Embodiment 10 MaterialsContent, wt %

20

15

5

5

5

5

19.9

25 Bis(tetra-n-butylammonium)tetracyanodiphenoquinodimethane 0.1

The texture is observed by using a microscope, and the liquid crystal isthe smectic I liquid crystal, has compact arrangement of crystaldomains, and has a good shading effect at the frosting state. Thetransmittance is tested as 90% at the clearing state and is merely 9% atthe frosting state, and the contrast is 10:1.

Embodiment 11 High Scattering Undefined Smectic Phase MischcrystalObtained by Using Various Smectic Liquid Crystal Materials for Mixing

TABLE 17 Composition of the mischcrystal of Embodiment 11 MaterialsContent, wt %

20

24

5.9

5

5

10

12

18 (ferrocenylmethyl)trimethylammonium iodide 0.1

FIG. 7 is a view of the texture of the mischcrystal of Embodiment 11(shot by using a 10× objective lens). The texture is observed aswater-like texture by using a microscope, and the liquid crystal is anundefined smectic phase, has compact arrangement of crystal domains, andhas a good shading effect at the frosting state. The transmittance istested as 90% at the clearing state and is merely 9% at the frostingstate, and the contrast is 10:1.

Embodiment 12 High Scattering Mixed Liquid Crystal Material Obtained byUsing the Alkyne Liquid Crystals

TABLE 18 Composition of the mischcrystal of Embodiment 12 MaterialsContent, wt %

54.9

20

10

5

5

5 Cetyltrimethylammonium perchlorate 0.1

The transmittance is tested as 90% at the clearing state and is 15% atthe frosting state, and the contrast is 6:1.

Embodiment 13 High Scattering Mixed Liquid Crystal Material Obtained byUsing Cyanoterphenyl Liquid Crystals

TABLE 19 Composition of the mischcrystal of Embodiment 13 MaterialsContent, wt %

44.9

20

5

5

5

15

5 Cetyltriethylammonium bromide 0.1

The transmittance is tested as 90% at the clearing state and is 15% atthe frosting state, and the contrast is 6:1.

Embodiment 14 High Scattering Mixed Liquid Crystal Material Obtained byUsing Polycyclic Materials for Mixing

TABLE 20 Composition of the mischcrystal of Embodiment 14 MaterialsContent, wt %

34

10

5

5

5

15

5

20

1

The transmittance is tested as 88% at the clearing state and is 11% atthe frosting state, and the contrast is 8:1.

Embodiment 15 High Scattering Mischcrystal Obtained by Adding Compoundsof Formula (III) to the Common Smectic A Phase Materials

TABLE 21 Composition of the mischcrystal of Embodiment 15 MaterialsContent, wt %

54.9

30

5

5

5 Cetyltrimethylammonium perchlorate 0.1

The transmittance is tested as 90% at the clearing state and is 15% atthe frosting state, and the contrast is 6:1.

Embodiment 1 High Scattering Mischcrystal Obtained by Adding Compoundsof Formula (IV) to the Common Smectic A Phase Materials

TABLE 22 Composition of the mischcrystal of Embodiment 16 MaterialsContent, wt %

54.9

30

5

5

5 Cetyltrimethylammonium perchlorate 0.1

The transmittance is tested as 90% at the clearing state and is 15% atthe frosting state, and the contrast is 6:1.

Embodiment 17 High Scattering Mischcrystal Obtained by Adding Compoundsof Formula (V) to the Common Smectic A Phase Materials

TABLE 23 Composition of the mischcrystal of Embodiment 17 MaterialsContent, wt %

54.9

30

5

5

5 Cetyltrimethylammonium perchlorate 0.1

The transmittance is tested as 90% at the clearing state and is 15% atthe frosting state, and the contrast is 6:1.

Embodiment 18 High Scattering Mischcrystal Obtained by Adding Compoundsof Formula (VI) to the Common Smectic A Phase Materials

TABLE 24 Composition of the mischcrystal of Embodiment 18 MaterialsContent, wt %

54.9

30

5

5

5 Cetyltrimethylammonium perchlorate 0.1

The transmittance is tested as 90% at the clearing state and is 15% atthe frosting state, and the contrast is 6:1.

Embodiment 19 High Scattering Mischcrystal Obtained by Using anyCombination of The Common Smectic A Phase Materials with Compounds ofFormula (III), (IV), (V) and (VI)

TABLE 25 Composition of the mischcrystal of Embodiment 19 MaterialsContent, wt %

54.9

30

5

5

5 Cetyltrimethylammonium perchlorate 0.1

The transmittance is tested as 90% at the clearing state and is 15% atthe frosting state, and the contrast is 6:1.

Embodiment 20 High Scattering Mischcrystal Obtained by Using anyCombination of The Common Smectic A Phase Materials with Compounds ofFormula (III), (IV), (V) and (VI)

TABLE 26 Composition of the mischcrystal of Embodiment 20 MaterialsContent, wt %

54.9

30

5

5

5 Cetyltrimethylammonium perchlorate 0.1

The transmittance is tested as 90% at the clearing state and is 15% atthe frosting state, and the contrast is 6:1.

Application of the High Scattering Smectic Liquid Crystal Material ofthe Present Invention in Display

A display device that uses a high scattering smectic material mainlyincludes a display layer, as shown in FIG. 8. The display layer includesa first base layer, a second base layer, and a mixed layer containingthe above high scattering smectic material disposed between the firstbase layer and the second base layer. The first base layer is providedwith a first conductive electrode layer on a side facing the mixedlayer, the second base layer is provided with a second conductiveelectrode layer on a side facing the mixed layer, and the firstconductive electrode layer and the second conductive electrode layerindependently include M electrodes and N electrodes (M,N≧1), and a pixelmatrix for displaying a static image is formed between the M electrodesand the N electrodes.

In general, the display layer is provided with a back layer on the back;in order to achieve color display, a color film is provided between thedisplay layer and the back layer; in order to optimize the opticalstructure of the display, a light enhancing layer is provided betweenthe display layer and the back layer, and the light enhancing layerincludes a light enhancing base plate and a light enhancing member.

The light enhancing base plate is a high molecular film or glass; andthe light enhancing member is a light enhancing film or prism structure.

The light enhancing member may be disposed on a surface of the lightenhancing base plate facing the display layer and/or the back layer, ormay be disposed on a surface of the first base layer facing the lightenhancing layer or/and on a surface of the second base layer facing thelight enhancing layer.

The light enhancing layer is designed to reflect and refract the lightincident into the display multiple times, to increase the number oftimes and the amount of the light incident into the display layer, sothat more light is refracted in the portion of the display layercorresponding to the pixel points that are required for displaying inthe frosting state, thereby improving the scattering effect andenhancing the luminance at the pixels in the frosting state, andsignificantly improving the contrast between the pixels in the frostingstate and the pixels in the full clearing state.

The display layer is shown in FIG. 8, and has been disclosed in theprior art, so the structure of the display layer is not described indetail herein. The back layer may be made of PET or PC or a plastic orpaper material, and the back layer may be black, white or other colors.The light enhancing layer is shown in FIG. 9 and is transparent, and hasa high light transmittance. The base plate is made of PET material, andthe light enhancing member may be a light enhancing film or prismstructure. The light enhancing film is a layer of resin film having ahigh refractive index in the range of 1.65 to 1.8, and the prismstructure is made of a resin having a high refractive index in the 1.65to 1.8. In practice, the resin film having a high refractive index maybe cut to obtain a prism structure. The prism structure disposed on thesurface of the base plate facing the display layer and the surface ofthe base plate facing the back layer may be set in a convex or concaveform, and the prism structure disposed on the surface of the base platefacing the display layer may be the same as or different from the prismstructure disposed on the surface of the base plate facing the backlayer.

The Mixed Layer of the Smectic Liquid Crystal Material

The mixed liquid crystal layer is generally formed by mixing the abovehigh scattering smectic material, a conductive materials, a spacer andsometimes a polymer.

1) The mixed layer is formed by mixing the above high scattering smecticmaterial, a conductive material and a spacer.

The smectic liquid crystal may be the high scattering smectic liquidcrystal material of the present invention.

The spacer is a spacer ball or spacer rod made of a polyester or apolystyrene or a glass material.

The composition of the mixed layer is: the high scattering smecticmaterial of 0.0002% to 99.99%, the conductive material of 0.0001% to10%, and the spacer of 0.0001% to 90%, based on the total weight of themixture.

2) The mixed layer contains a mixture encapsulated in the polymerstructure and formed by the high scattering smectic material, aconductive material and a spacer:

The smectic liquid crystal may be the high scattering smectic liquidcrystal material of the present invention.

The spacer is a spacer ball or spacer rod made of a polyester or apolystyrene or a glass material.

The polymer structure is formed by a monomer material or polymermaterial, and is directly printed or etched or nano-imprinted orjet-printed on an inner surface of a corresponding layer, and isthermally or UV cured into a polymer material having a given structure.The monomer material is any one of an epoxy resin monomer, apolyacrylate monomer or a polymethacrylate monomer.

The composition of the mixed layer is: the high scattering smecticmaterial of 0.0002% to 99.99%, the polymer material of 0.0001% to 80%,the conductive material of 0.0001% to 10%, and the spacer of 0.0001% to80%, based on the total weight of the mixture.

The polymer structure forms an accommodation cavity for accommodating amixture formed by the high scattering smectic material, the conductivematerial and the spacer, and the polymer structure is in the form ofregular ball, micro-cylinder, fiber, hemisphere, parallel strip, cube,rectangle, cross-wire form, network structure, square grating structure,irregular polygonal structure, or any of combinations thereof. Thepolymer structure is uniform or non-uniform, and is miscible ordispersible with the high scattering smectic material, the conductivematerial and the spacer, or contacted or spaced with the high scatteringsmectic material, the conductive material and the spacer.

The high scattering smectic material of the present invention may alsobe filled between two plastic films or two pieces of glass having aconducting layer to serve as a dimming medium, and may be filled invacuum into a lattice screen to serve as a display device.

In order to control the thickness of the crystal liquid cell, in thehigh scattering smectic material of the present invention, a spacer ballor spacer rod made of polyester or polystyrene—or a glass material maybe added; in order to reduce the working viscosity and improve thebonding firmness of the liquid crystal cell, a prepolymer may be addedin the high scattering smectic material; and in order to achieve theeffect of color display, a dichroic dye may be added in the highscattering smectic material.

The high scattering liquid crystal material of the present invention isapplied to a smectic display device, so as achieve the application ofthe high scattering liquid crystal material in a display, by means ofthe excellent optical structure and drive method of the smectic displaydevice. Application of the high scattering liquid crystal materials canprovide a smectic liquid crystal display having an excellent opticalstructure.

The application of the high scattering smectic material of the presentinvention is not limited to using as the material in the dimming mediumor a display device, and the high scattering smectic material of thepresent invention can be used in all of the devices with adual-frequency drive mode of low-frequency frosting and high-frequencyclearing.

What is claimed is:
 1. A high scattering smectic liquid crystalmaterial, comprising: two or more compounds of Formula (I),

wherein R₁ is C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀ alkenyl, C₁-C₂₀alkenyloxy, silanyl, siloxanyl and halogenated groups thereof; andC₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀ alkenyl, C₁-C₂₀ alkenyloxy, silanyland siloxanyl and isomers thereof with any —CH₂— substituted with —O—,—S—, —CF₂—, —CF₂O—, —CO—, —COO—, —O—CO—, —O—COO—, —CF═CF—, —CH═CF—,—CF═CH— or —CH═CH—; R₂ is CN, F, NCS, NCO, CF₃, CHF₂, CH₂F, OCF₃, OCHF₂,OCH₂F, NO₂, Cl, CH═CF₂ and OCH═CF₂; C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀alkenyl, C₁-C₂₀ alkenyloxy, silanyl, siloxanyl and halogenated groupsthereof; and C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀ alkenyl and C₁-C₂₀alkenyloxy and isomers thereof with any —CH₂— substituted with —O—, —S—,—CF₂—, —CF₂O—, —CO—, —COO—, —O—CO—, —O—COO—, —CF═CF—, —CH═CF—, —CF═CH—or —CH═CH—; A, B, C and D each has a rigid ring structure and eachindependently comprises:

or cycloalkenyl; wherein the hydrogen atoms on the ring structures areeither unsubstituted or independently substituted; Z₁, Z₂, and Z₃ areindependently: a single bond, C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀alkenyl, C₁-C₂₀ alkenyloxy, silanyl and siloxanyl; and C₁-C₂₀ alkyl,C₁-C₂₀ alkoxy, C₁-C₂₀ alkenyl, C₁-C₂₀ alkenyloxy, silanyl and siloxanyland isomers thereof with any —CH₂— substituted with —O—, —S—, —CO—,—COO—, —O—CO—, —O—COO, —CF═CF—, —CHF—, —CF₂—, —CF₂O—, —CH₂O—, —OCH₂—,—CH═CH—, —CH═N—, —CH═N—N═CH—, —CH═CF—, —CF═CH—, —CH₂CF₂—, —CF₂CH₂— or

X₁ to X₁₄ are independently: H, CN, NCS, F, Cl, CF₃, CHF₂, CH₂F, OCF₃,OCHF₂, OCH₂F, NO₂, alkyl or alkoxy; and M1, M2, M3 and M4 areindependently 0, 1 or 2, and M1+M2+M3+M4≧2; and one or more ioniccompounds of Formula (II),R₃—X⁺Y⁻  Formula (II) wherein R₃ is: C₀-C₂₀ alkyl, C₀-C₂₀ alkoxy, C₀-C₂₀alkenyl and C₀-C₂₀ alkenyloxy and halogenated groups thereof;ferrocenylmethyl and phenyl; and C₀-C₂₀ alkyl, C₀-C₂₀ alkoxy, C₀-C₂₀alkenyl and C₀-C₂₀ alkenyloxy and isomers thereof with any —CH₂—substituted with —O—, —S—, —CF₂—, —CF₂O—, —CO—, —COO—, —O—CO—, —O—COO—,—CF═CF—, —CH═CF—, —CF═CH—, —CH═CH—,

or phenyl; X⁺ is a cation selected from the group consisting of: Na⁺,K⁺, N⁺, [(R₄)₃]N⁺, [(R₄)₃]P⁺,

wherein R₄ is C₁-C₃₀ alkyl, C₁-C₃₀ alkoxy, C₁-C₃₀ alkenyl, C₁-C₃₀alkenyloxy or halogenated groups thereof, or phenyl; and R₅ is C₁-C₃₀alkyl, C₁-C₃₀ alkoxy, C₁-C₃₀ alkenyl, C₁-C₃₀ alkenyloxy, or halogenatedgroups thereof, or phenyl; and Y⁻ is an anion selected from the groupconsisting of: F⁻, Cl⁻, Br⁻, I⁻, (PF₆)⁻, (Ph₄B)⁻, SO₄ ⁻, ClO₄ ⁻ and


2. The high scattering smectic liquid crystal material of claim 1,wherein in the compounds of Formula (I): R₁ is: C₁-C₁₅ alkyl, C₁-C₁₅alkoxy, C₁-C₁₅ alkenyl, C₁-C₁₅ alkenyloxy, silanyl, siloxanyl andhalogenated groups thereof, C₁-C₁₅ alkyl, C₁-C₁₅ alkoxy, C₁-C₁₅ alkenyl,C₁-C₁₅ alkenyloxy, or silanyl and siloxanyl and isomers thereof with any—CH₂— substituted with —O— or —S—; R₂ is: CN, F, NCS, CF₃, CHF₂, CH₂F,OCF₃, OCHF₂, OCH₂F, Cl; C₁-C₁₅ alkyl, C₁-C₁₅ alkoxy, C₁-C₁₅ alkenyl,C₁-C₁₅ alkenyloxy, silanyl and siloxanyl and halogenated groups thereof,C₁-C₁₅ alkyl, C₁-C₁₅ alkoxy, or C₁-C₁₅ alkenyl and C₁-C₁₅ alkenyloxy andisomers thereof with —CH₂— substituted with —O— or —S—; A, B, C and Dare independently selected from the group consisting of:

Z₁ to Z₃ are independently selected from the group consisting of: asingle bond, —C₂H₄—, —CH═CH—, —C≡C—, —CF₂O—, —CH₂O—, —COO— and—CH═N—N═CH—; X₁ to X₁₄ are independently selected from the groupconsisting of: H, CN, NCS, F, Cl and CF₃; and M1, M2, M3 and M4 areindependently 0 or 1, and M1+M2+M3+M4≧2.
 3. The high scattering smecticliquid crystal material of claim 2, wherein in the compounds of Formula(I): R₁ is selected from the group consisting of: C₁-C₁₀ alkyl, C₁-C₁₀alkoxy, C₁-C₁₀ alkenyl, silanyl, siloxanyl and halogenated groupsthereof, C₁-C₁₀ alkyl, C₁-C₁₀ alkoxy, C₁-C₁₀ alkenyl, silanyl, andsiloxanyl and isomers thereof with any —CH₂— in the groups substitutedwith —O—; R₂ is CN, F, NCS, CF₃ or OCF₃; A, B, C and D are independentlyselected from the group consisting of:

Z₁ to Z₃ are independently selected from the group consisting of: asingle bond, —C₂H₄—, —CH═CH—, —C≡C—, —CF₂O—, —CH₂O— and —COO—; and X₁ toX₁₄ are independently selected from the group consisting of: H, CN, Fand Cl.
 4. The high scattering smectic liquid crystal material of claim3, wherein the compounds of Formula (I) are alkynes having a structureof Formula (III),

wherein R₆ is C₁-C₁₀ alkyl or C₁-C₁₀ alkoxy; R₇ is CN, NCS or F; E and Fare independently selected from the group consisting of:

X₁₅ to X₂₀ are independently H or F; and M₅ and M₆ are independently 0or
 1. 5. The high scattering smectic liquid crystal material of claim 3,wherein the compounds of Formula (I) are heterocyclic compounds having astructure of Formula (IV),

wherein R₈ is C₁-C₁₀ alkyl or C₁-C₁₀ alkoxy; R₉ is CN, NCS or F; G and Hare independently selected from the group consisting of:

X₂₁ to X₂₂ are independently H or F; and M₇ and M₈ are independently 0or 1, and M₇+M₈≧1.
 6. The high scattering smectic liquid crystalmaterial of claim 3, wherein the compounds of Formula (I) are difluoroether compounds having a structure of Formula (V),

wherein R₁₀ is C₁-C₁₀ alkyl or C₁-C₁₀ alkoxy; R₁₁ is CN, NCS or F; I isa ring structure selected from the group consisting of:

X₂₃ to X₂₈ are independently H or F; and M₉ is 0 or
 1. 7. The highscattering smectic liquid crystal material of claim 3, wherein thecompound of Formula (I) are polycyclic biphenyl compounds having astructure of Formula (VI),

wherein R₁₂ is C₁-C₁₀ alkyl or C₁-C₁₀ alkoxy; R₁₃ is CN, NCS or F; J andK are ring structures independently selected from the group consistingof:

Z₄ is selected from the group consisting of: a single bond, —COO—,—C₂H₄— and; X₂₉ to X₃₂ are independently H or F; and M₁₀ and M₁₁ areindependently 0 or
 1. 8. The high scattering smectic liquid crystalmaterial of claim 3, wherein the high scattering smectic liquid crystalmaterial comprises a smectic A, B, C, D, E, F, G, H or I phase liquidcrystal material.
 9. The high scattering smectic liquid crystal materialof claim 8, wherein the high scattering smectic liquid crystal materialfurther comprises at least one compound selected from the groupconsisting of: alkyne compounds, heterocyclic compounds, difluoro ethercompounds and polycyclic biphenyl compounds.
 10. The high scatteringsmectic liquid crystal material of claim 1, wherein in the ioniccompound of Formula (II), R₃ is selected from the group consisting of:C₀-C₁₆ alkyl, C₀-C₁₆ alkoxy, C₀-C₁₆ alkenyl, C₀-C₁₆ alkenyloxy,ferrocenylmethyl and phenyl; and C₀-C₁₆ alkyl, C₀-C₁₆ alkoxy, C₀-C₁₆alkenyl and C₀-C₁₆ alkenyloxy and isomers thereof with any —CH₂—substituted with —O—, —S—, and phenyl;

X⁺ is a cation selected from the group consisting of: Na⁺, K⁺, N⁺,[(R₄)₃]N⁺, [(R₄)₃]P⁺,

wherein R₄ is C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀ alkenyl, C₁-C₂₀alkenyloxy, or halogenated groups thereof, or phenyl; and R₅ is C₁-C₂₀alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀ alkenyl, C₁-C₂₀ alkenyloxy, or halogenatedgroups thereof, and phenyl; and Y⁻ is an anion selected from the groupconsisting of: F⁻, Cl⁻, Br⁻, (PF₆)⁻, (Ph₄B)⁻, SO₄ ⁻, ClO₄ ⁻, and


11. The high scattering smectic liquid crystal material of claim 10,wherein in the ionic compound of Formula (II), R₃ is selected from thegroup consisting of: C₀-C₁₆ alkyl, phenyl, C₀-C₁₆ heteroalkyl with any—CH₂— substituted with

or phenyl, and isomers thereof; X⁺ is a cation selected from the groupconsisting of: Na⁺, K⁺, N⁺, [(R₄)₃]N⁺[(R₄)₃]P⁺,

wherein R₄ is C₁-C₁₆ alkyl or phenyl; and R₅ is C₁-C₁₆ alkyl or phenyl;and Y⁻ is an anion selected from the group consisting of: F⁻, Cl⁻, Br⁻,(PF₆)⁻, (Ph₄B)⁻, SO₄ ⁻ and ClO₄ ⁻.
 12. The high scattering smecticliquid crystal material of claim 11, wherein the ionic compounds arecompounds having a structure of Formula (VII),

wherein R is selected from the group consisting of: C₀-C₁₆ alkyl andC₀-C₁₆ terminal alkenyl; and X⁻ is an anion selected from the groupconsisting of: F⁻, Cl⁻, Br⁻, (PF₆)⁻, (Ph₄B)⁻, SO₄ ⁻ and ClO₄ ⁻.
 13. Thehigh scattering smectic liquid crystal material of claim 1, wherein thehigh scattering smectic liquid crystal material is a smectic A phasematerial, or a non-smectic A phase material having a degree of orderhigher than that of the smectic A phase.
 14. The high scattering smecticliquid crystal material of claim 13, wherein the compound of Formula (I)is 1% to 99.9999% of the total weight of a mixed liquid crystal layer,and the ionic compounds of Formula (II) is 0.0001% to 10% of the totalweight of the mixed liquid crystal.
 15. The high scattering smecticliquid crystal material of claim 1, wherein a spacer ball, a spacer rod,a prepolymer or a dichroic dye made of a polyester material, apolystyrene material, or a glass material, is further added to the highscattering smectic liquid crystal material.
 16. A device comprising ahigh scattering smectic liquid crystal material, wherein the highscattering smectic liquid crystal material comprises two or morecompounds of Formula (I) and one or more ionic compounds of Formula(II):

R₃—X⁺Y⁻  Formula (II) wherein R₁ is C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀alkenyl, C₁-C₂₀ alkenyloxy, silanyl, siloxanyl and halogenated groupsthereof; and C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀ alkenyl, C₁-C₂₀alkenyloxy, silanyl and siloxanyl and isomers thereof with any —CH₂—substituted with —O—, —S—, —CF₂—, —CF₂O—, —CO—, —COO—, —O—CO—, —O—COO—,—CF═CF—, —CH═CF—, —CF═CH— or —CH═CH—; R₂ is CN, F, NCS, NCO, CF₃, CHF₂,CH₂F, OCF₃, OCHF₂, OCH₂F, NO₂, Cl, CH═CF₂ and OCH═CF₂; C₁-C₂₀ alkyl,C₁-C₂₀ alkoxy, C₁-C₂₀ alkenyl, C₁-C₂₀ alkenyloxy, silanyl, siloxanyl andhalogenated groups thereof; and C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀alkenyl and C₁-C₂₀ alkenyloxy and isomers thereof with any —CH₂—substituted with —O—, —S—, —CF₂—, —CF₂O—, —CO—, —COO—, —O—CO—, —O—COO—,—CF═CF—, —CH═CF—, —CF═CH— or —CH═CH—; A, B, C and D each has a rigidring structure and each independently comprises:

or cycloalkenyl; wherein the hydrogen atoms on the ring structures areeither unsubstituted or independently substituted; Z₁, Z₂, and Z₃ areindependently: a single bond, C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, C₁-C₂₀alkenyl, C₁-C₂₀ alkenyloxy, silanyl and siloxanyl; and C₁-C₂₀ alkyl,C₁-C₂₀ alkoxy, C₁-C₂₀ alkenyl, C₁-C₂₀ alkenyloxy, silanyl and siloxanyland isomers thereof with any —CH₂— substituted with —O—, —S—, —CO—,—COO—, —O—CO—, —O—COO, —CF═CF—, —CHF—, —CF₂—, —CF₂O—, —CH₂O—, —OCH₂—,—CH═CH—, —CH═N—, —CH═N—N═CH—, —CH═CF—, —CF═CH—, —CH₂CF₂—, —CF₂CH₂— or

X₁ to X₁₄ are independently: H, CN, NCS, F, Cl, CF₃, CHF₂, CH₂F, OCF₃,OCHF₂, OCH₂F, NO₂, alkyl or alkoxy; M1, M2, M3 and M4 are independently0, 1 or 2, and M1+M2+M3+M4≧2; wherein R₃ is: C₀-C₂₀ alkyl, C₀-C₂₀alkoxy, C₀-C₂₀ alkenyl and C₀-C₂₀ alkenyloxy and halogenated groupsthereof; ferrocenylmethyl and phenyl; and C₀-C₂₀ alkyl, C₀-C₂₀ alkoxy,C₀-C₂₀ alkenyl and C₀-C₂₀ alkenyloxy and isomers thereof with any —CH₂—substituted with —O—, —S—, —CF₂—, —CF₂O—, —CO—, —COO—, —O—CO—, —O—COO—,—CF═CF—, —CH═CF—, —CF═CH—, —CH═CH—,

or phenyl; X⁺ is a cation selected from the group consisting of: Na⁺,K⁺, N⁺, [(R₄)₃]N⁺, [(R₄)₃]P⁺,

wherein R₄ is C₁-C₃₀ alkyl, C₁-C₃₀ alkoxy, C₁-C₃₀ alkenyl, C₁-C₃₀alkenyloxy or halogenated groups thereof, or phenyl; and R₅ is C₁-C₃₀alkyl, C₁-C₃₀ alkoxy, C₁-C₃₀ alkenyl, C₁-C₃₀ alkenyloxy, or halogenatedgroups thereof, or phenyl; and Y⁻ is an anion selected from the groupconsisting of: F⁻, Cl⁻, Br⁻, I⁻, (PF₆)⁻, (Ph₄B)⁻, SO₄ ⁻, ClO₄ ⁻ and

and wherein the device has a capacitor capable of applying electricenergy in dual waveforms, one waveform is high-frequency drive pulse forclearing operation, and the other waveform is low-frequency drive pulsefor frosting operation.